The present invention relates to a disposable syringe device having a retractable needle or cannula. More particularly, the present invention relates to a disposable syringe which allows the needle to be retracted, once it has been used, to a position of safety so as to prevent personal contact with the needle tip.
The viral disease AIDS has become of great concern to health professionals because of its obvious potentially devastating impact on the health and monetary resources of this country. To date, the only "cure" which amounts to control, is through prevention of the spread of this uniformly fatal disease. The newest high-risk group is health care professionals.
Not only do known AIDS patients represent a source for the spread of disease among health care workers but so does the general population. There are large groups of people who have been exposed as intravenous drug users, people who have received blood transfusions during a certain period of time when there was no testing, and people who have been infected with the virus through sexual contact.
Health care workers, in addition, may be exposed within the hospital environment by contact with body secretions but, in particular, through accidental needle punctures.
Commercially available disposable syringes have certain generic characteristics and components which are used industry-wide. Indeed, many of these parts are interchangeable from manufacturer to manufacturer.
Previous syringe devices are described in the following U.S. patents: U.S. Pat. No. 4,026,287 to Haller; U.S. Pat. No. 4,507,117 to Vining et al.; U.S. Pat. No. 4,650,468 to Jennings; U.S. Pat. No. 4,675,005 to DeLuccia; U.S. Pat. No. 4,710,170 to Haber et al.; U.S. Pat. No. 4,747,830 to Gloyer et al.; U.S. Pat. No. 4,770,655 to Haber et al.; U.S. Pat. No. 4,790,822 to Haining; U.S. Pat. No. 4,801,295 to Spencer; U.S. Pat. No. 4,804,370 to Haber et al.; and U.S. Pat. No. 4,808,169 to Haber et al.
By the present invention, there is provided an improved syringe having a unique mechanism which allows the exposed needle after use to be easily withdrawn to safety within the syringe without the need for breakage of any portion of the device. Use of the syringe of the present invention virtually eliminates the potential for the health care worker to be stuck by an infected needle.
The present syringe has a threaded extension or threadlock at the forward end of the plunger which replaces the strut of the generic model. The threadlock passes through a fluid-tight threadport extending axially through the center of the rubber piston. In the post injection state the plunger threadlock has entered a threadbore element which is secured to the needle. The threadlock and threadbore may be easily engaged by a simple clockwise turn of the plunger. Upon engagement of the threadlock with the threadbore, the entire threadbore assembly, including gasket, hub and ultimately the needle, may be withdrawn safely into the syringe cylinder. At the base of the syringe cylinder, stop elements are positioned to prevent the plunger assembly from being removed from the back side of the syringe, further protecting the operator.